Elimination Reactions of Halogenoalkanes
- In an elimination reaction, an organic molecule loses a small molecule
- In the case of halogenoalkanes, this small molecule is a hydrogen halide (eg. HCl)
- The halogenoalkanes are heated with ethanolic sodium hydroxide causing the C-X bond to break heterolytically, forming an X- ion and leaving an alkene as an organic product
- For example, bromoethane reacts with ethanolic sodium hydroxide when heated to form ethene
The elimination reaction of bromoethane with ethanolic sodium hydroxide
Hydrogen bromide is eliminated to form ethene
Examiner Tip
The reaction conditions in a reaction are extremely important
If NaOH(ethanol) is used, an elimination reaction takes place to form an alkene from a halogenoalkane
If NaOH(aq) is used, a nucleophilic substitution reaction takes place to form an alcohol from a halogenoalkane.
